Performance of an Item Response Theory-Based Computer Adaptive Test in Identifying Functional Decline

Cheville AL, Yost KJ, Larson DR, Dos Santos K, O'Byrne MM, Chang MT, Therneau TM, Diehn FE, Yang P. Performance of an item response theory-based computer adaptive test in identifying functional decline.ObjectiveTo achieve a low respondent burden and increase the responsiveness of functional measurement by using an item response theory-based computer adaptive test (CAT), the Activity Measure for Post-Acute Care (AM-PAC) CAT.DesignTwo-year prospective cohort study.SettingTelephonic assessments from a quaternary medical center.ParticipantsPatients (N=311) with late-stage lung cancer (LC).InterventionsMonthly assessments for up to 2 years. Disease progression was determined via record abstraction. Anchor-based responsiveness techniques were used to compare AM-PAC-CAT score changes between global rating of change (GRC) question response levels, as well as between intervals when adverse clinical events or symptom worsening did and did not occur. Distribution-based responsiveness assessments included calculation of the standardized effect size (SES) and standardized response mean (SRM).Main Outcome MeasuresAM-PAC-CAT, symptom numerical rating scales, and a GRC.ResultsAdministration time averaged 112 seconds over 2543 interviews. AM-PAC-CAT score changes became more positive as GRC responses reflected more improved states: a lot worse (−11.62), a little worse (−1.92), the same (−.10), a little better (1.01), and a lot better (2.82). Score changes were negative when associated with adverse clinical events. The SES and SRM for score differences between 1 to 2 and 9 to 10 months prior to death were −.87 and −1.13, respectively. The minimally important difference estimate was defined by the mean CAT session SE at 2.0.ConclusionsThe AM-PAC-CAT imposes a low, <2-minute, respondent burden, and distribution- and anchor-based methods suggest that is moderately responsive in patients with late-stage LC.